1. Field of the Invention
The present invention relates to a read-once record medium, and more particularly to a record medium with a sensitive layer, thereby, the structure of the sensitive layer or the data substrate will be changed (or destroyed) when laser beams with specific power emitted from an optical storage device pass through the data substrate and focus on the sensitive layer, and the laser beams will be reflected by the sensitive layer and can not be recognized by the optical storage device.
2. Description of the Related Art
In general, audio and video files can be downloaded from a server and played in a DVD or CD player by means of a simple security check according to a prior art. However, the security check may be skipped by users, and thus DVD or CD publishers cannot request users to pay for the downloaded files and thus the unauthorized use of DVD or CD media becomes more and more.
At present, there are systems or solutions that can solve the problem of protecting DVD or CD from unauthorized copying. For example, U.S. Pat. No. 5,991,403 issued to Aucsmith, et al disclosed a method for encoding MPEG compatible video data for subsequent compression that comprises detecting a plurality of frames of video data organized as a GOP, generating an encryption key for the GOP, and encrypting the video data using GOP-synchronized substitution, transposition, and rotation transformations that are parameterized by offsets derived from the generated encryption key.
U.S. Pat. No. 5,915,018 issued to Aucsmith, et al disclosed a cryptographic system and method for secure distribution and management of cryptographic keys for use in a DVD copy protection scheme. A DVD disc having compressed, encrypted content written on a first portion of the disc, and the content encryption key, itself encrypted with a second key and written out of band on a second portion of the disc is used to provide content, key, and control information to a DVD player.
U.S. Pat. No. 5,991,403 is used for coding MPEG compatible video data for subsequent compression, and U.S. Pat. No. 5,915,018 is a cryptographic system and method for secure distribution and management of cryptographic keys for use in a DVD copy protection scheme. However, these patented technologies do not provide a system or a method for portable devices, and the portable device including but not limited to a portable medium player having an LCD display device can legally download audio files and video file in a DVD or CD and play the file from the portable device.